Official Pest Reports are provided by National Plant Protection Organizations within the NAPPO region. These Pest Reports are intended to
comply with the International Plant Protection Convention's Standard on Pest Reporting, endorsed
by the Interim Commission on Phytosanitary Measures in March 2002.

Chrysanthemum White Rust (CWR) in Connecticut and Michigan - United States

Date posted: 09/04/2008

Contact: Dr. Anwar Rizvi, (301) 734-4313

On August 20, APHIS confirmed the detection of CWR, Puccinia horiana P. Henn., in suspect samples collected from mums planted outdoors at a home in Norwalk, Connecticut. The samples were submitted to APHIS for confirmation by the Connecticut Agricultural Experiment Station. It was reported that the resident of the affected premises bought eight plants last year and planted them in the ground last fall. The affected plants were destroyed on August 21, 2008, and a delimiting survey was conducted approximately 400 meters around the affected garden site. No other chrysanthemums were found in the area.

On August 7, APHIS confirmed the detection of CWR in suspect chrysanthemum specimens from a nursery in Grand Blanc, Michigan. The Michigan Department of Agriculture (MDA) submitted the samples to APHIS for confirmation. This is the first CWR detection to occur in a nursery setting this year.

The affected Michigan nursery received approximately 600 cuttings from a nursery in Pennsylvania on August 12, 2008, and noted that a number of these plants were dying. The dying samples were sent to MDA to identify the cause. As a result of this detection, APHIS issued an Emergency Action Notice and the nursery agreed to destroy all plants at the site via deep burial, under the supervision of APHIS and MDA inspectors. All equipment associated with the potting of, movement, and burying of the infected plant material was disinfected with a bleach solution. The affected nursery did not sell any plants. The area where the infected chrysanthemum plants were grown and stored will not be used until next year.

APHIS is also working with the Pennsylvania Department of Agriculture to inspect mums from the nursery that sent cuttings to the affected Michigan nursery. This Pennsylvania nursery consists of 7 acres of field-grown mums. No symptomatic plants were found.

CWR is of plant quarantine importance in the United States. This fungal disease primarily attacks cultivars of mums grown for flower production and could have significant impact if it becomes established and is transported into greenhouses or nurseries.

Under IPPC Standards, Puccinia horiana is considered to be a pest that is transient, actionable, and under eradication in the United States.